Effect of Hafnium Coating on Osseointegration of Titanium Implants: A Split Mouth Animal Study

The behaviour of hafnium as surface coating in biological environments has not been studied. Little is known about osseointegration of hafnium-coated titanium implants. Thus, further studies of hafnium coating under biological conditions are required in order to determine the suitability of this material, as a surface coating for biomedical application. The aim of the study is to analyse the difference between hafnium-coated titanium and uncoated titanium by evaluating the osseointegration ability of hafnium metal and mechanism of which promotes better bone integration. The study was conducted with a split mouth design on 16 Wistar Albino rats of both sexes, at the age of 6-7 months, weighing 2526.5 ± 74.4 g . Self-tapping titanium osteosynthesis screws ( 4 mm × 2 mm ) (LeForte System Bone Screw®) were implanted in the mandible of rats: Group A (pure titanium screws, n = 12 ) and Group B (hafnium-coated screws, n = 12 ). The implanted screws’ stability was checked and noted with a specially customised torque apparatus during insertion and removal of implant. The tissue sections were then processed for hematoxylin and eosin and Masson’s trichrome for bone and connective tissue examination, after 4 and 8 weeks of placement. Hafnium coating appears to have offered similar biocompatibility (aspartate transaminase (AST), alanine aminotransferase (ALT), and creatine kinase (CK) enzyme assay), statistically significant improvement (independent Student’s t -test, p < 0.05 ) in insertion torque ( 25.42 ± 3.965 ) and removal torque ( 29.17 ± 2.887 ) than commercially pure titanium with insertion torque ( 22.08 ± .575 ) and removal torque ( 25.42 ± 2.575 ). Hafnium coating in the rat mandible showed promising osseointegration with good tissue biocompatibility. Further human trials of hafnium-coated implants are needed to understand the biological behaviour better to enhance clinical performance.

Bioabsorbable implants in forefoot surgery: a review of materials, possibilities and disadvantages

Bioabsorbable and biodegradable implants offer new possibilities in orthopaedic and trauma surgery. As soon as the initial stability of the degradable implants has reached the qualities of conventional materials, new devices may find usage in younger and more demanding patients. Residual conventional osteosynthetic material or the necessity to remove metal increasingly seems to be more of an adverse event than daily practice in forefoot surgery. Nevertheless, some drawbacks need to be discussed. Recent literature screened for the use of bioabsorbable and biodegradable materials in forefoot surgery, available implants and indications in forefoot surgery were analysed and summarized. Apart from common indications in forefoot surgery, points of interest were the type of biomaterial, the process of biodegradation and biointegration, and possible adverse events. Materials were comprehensively discussed for each indication based on the available literature. Polylactide, polyglycoside and polydioxanone are considered safe and sufficiently stable for use in forefoot surgery. Low complication rates (e.g. 0.7% for pin fixation in hallux deformities) are given. Magnesium implants suffered from an extensive corrosive process in the first generation but now seem to be safe in forefoot surgery and offer good options compared with conventional titanium screws, especially in procedures of the first ray. Allograft bone has proven feasibility in small case series, but still lacks larger or randomized clinical trials. The first results are promising. Bioresorbable and osseointegrating devices offer attractive new possibilities for surgeons and patients. Despite all the known advantages, the difficulties and possible complications must not be forgotten, such as soft tissue reactions, unwanted osteolysis and a lower primary mechanical load capacity. Cite this article: EFORT Open Rev 2021;6:1132-1139. DOI: 10.1302/2058-5241.6.200157

Is the magnesium screw as stable as the titanium screw in the fixation of first metatarsal distal chevron osteotomy? A comparative biomechanical study on sawbones models

Background: Distal chevron osteotomy (DCO) is commonly performed in hallux valgus surgery. The fixation of the osteotomy is provided by various implants. The usage of biodegradable implants such as magnesium is gradually increasing due to the advantages they provide. In this study, we aimed to compare the fixation of DCO with magnesium or titanium screw biomechanically. Methods: Twenty sawbones were used. The samples were divided into two equal groups, including ten sawbones for fixation with single headless titanium (group-1) or magnesium screw (group-2). DCO and screw fixations were performed on all samples using the same technique. Biomechanical testing was applied to five samples in each group in cantilever and the other five in a physiological configuration using a computer connected to the electromechanical test machine. The obtained data were evaluated using the Shapiro–Wilk test, Student’s t-test and Mann–Whitney U test on the IBM® SPSS (Statistical Package for the Social Sciences) V22.0 software. Significance was accepted at the p < 0.05 level. Results: There was no statistically significant difference between the magnesium screw and the titanium screw in terms of maximum force, maximum displacement and stiffness measurements in cantilever and physiological loadings ( p > 0.05 for all). Conclusion: This study found no significant difference in biomechanical stability between the magnesium and titanium screws in DCO fixation on sawbones. Further studies with real bones are needed.

Comparison of metal artifact reduction techniques in magnetic resonance imaging of carbon-reinforced PEEK and titanium spinal implants

Background Carbon-reinforced PEEK (C-FRP) implants are non-magnetic and have increasingly been used for the fixation of spinal instabilities. Purpose To compare the effect of different metal artifact reduction (MAR) techniques in magnetic resonance imaging (MRI) on titanium and C-FRP spinal implants. Material and Methods Rod-pedicle screw constructs were mounted on ovine cadaver spine specimens and instrumented with either eight titanium pedicle screws or pedicle screws made of C-FRP and marked with an ultrathin titanium shell. MR scans were performed of each configuration on a 3-T scanner. MR sequences included transaxial conventional T1-weighted turbo spin echo (TSE) sequences, T2-weighted TSE, and short-tau inversion recovery (STIR) sequences and two different MAR-techniques: high-bandwidth (HB) and view-angle-tilting (VAT) with slice encoding for metal artifact correction (SEMAC). Metal artifact degree was assessed by qualitative and quantitative measures. Results There was a much stronger effect on artifact reduction with using C-FRP implants compared to using specific MRI MAR-techniques (screw shank: P < 0.001; screw tulip: P < 0.001; rod: P < 0.001). VAT-SEMAC sequences were able to reduce screw-related signal loss artifacts in constructs with titanium screws to a certain degree. Constructs with C-FRP screws showed less artifact-related implant diameter amplification when compared to constructs with titanium screws ( P < 0.001). Conclusion Constructs with C-FRP screws are associated with significantly less artifacts compared to constructs with titanium screws including dedicated MAR techniques. Artifact-reducing sequences are able to reduce implant-related artifacts. This effect is stronger in constructs with titanium screws than in constructs with C-FRP screws.

Highly precise navigation at the lateral skull base by the combination of flat-panel volume CT and electromagnetic navigation

This study aimed to evaluate the feasibility and accuracy of electromagnetic navigation at the lateral skull base in combination with flat panel volume computed tomography (fpVCT) datasets. A mastoidectomy and a posterior tympanotomy were performed on 10 samples of fresh frozen temporal bones. For registration, four self-drilling titanium screws were applied as fiducial markers. Multi-slice computed tomography (MSCT; 600 µm), conventional flat panel volume computed tomography (fpVCT; 466 µm), micro-fpVCT (197 µm) and secondary reconstructed fpVCT (100 µM) scans were performed and data were loaded into the navigation system. The resulting fiducial registration error (FRE) was analysed, and control of the navigation accuracy was performed. The registration process was very quick and reliable with the screws as fiducials. Compared to using the MSCT data, the micro-fpVCT data led to significantly lower FRE values, whereas conventional fpVCT and secondary reconstructed fpVCT data had no advantage in terms of accuracy. For all imaging modalities, there was no relevant visual deviation when targeting defined anatomical points with a navigation probe. fpVCT data are very well suited for electromagnetic navigation at the lateral skull base. The use of titanium screws as fiducial markers turned out to be ideal for comparing different imaging methods. A further evaluation of this approach by a clinical trial is required.

Silane-Coating Strategy for Titanium Functionalization Does Not Impair Osteogenesis In Vivo

Silane-coating strategy has been used to bind biological compounds to the titanium surface, thereby making implant devices biologically active. However, it has not been determined if the presence of the silane coating itself is biocompatible to osseointegration. The aim of the present study was to evaluate if silane-coating affects bone formation on titanium using a rabbit model. For this, titanium screw implants (3.75 by 6 mm) were hydroxylated in a solution of H2SO4/30% H2O2 for 4 h before silane-coating with 3-aminopropyltriethoxysilane (APTES). A parallel set of titanium screws underwent only the hydroxylation process to present similar acid-etched topography as a control. The presence of the silane on the surface was checked by x-ray photoelectron spectroscopy (XPS), with scanning electron microscopy (SEM) and atomic force microscopy (AFM). A total of 40 titanium screws were implanted in the tibia of ten New Zealand rabbits in order to evaluate bone-to-implant contact (BIC) after 3 weeks and 6 weeks of healing. Silane-coated surface presented higher nitrogen content in the XPS analysis, while micro- and nano-topography of the surface remained unaffected. No difference between the groups was observed after 3 and 6 weeks of healing (p > 0.05, independent t-test), although an increase in BIC occurred over time. These results indicate that silanization of a titanium surface with APTES did not impair the bone formation, indicating that this can be a reliable tool to anchor osteogenic molecules on the surface of implant devices.

Rhinotheca Prosthesis in a Carcará (Caracara plancus)

Background: The bird’s beak is a structure in constant growth, covered by keratinized epidermal sheaths called rhamphotheca. When subjected to certain degrees of injury, birds can suffer from lesions and fractures in different parts of the body, including the beak. One can treat simple ranch lesions by antisepsis and covering it with resin while the keratin is replaced; yet in complete fractures, with segment avulsion, they need complex prostheses to restore the functions of the nozzle. The main goal of this study was to report a case of a synthetic rhinotheca prosthesis placement in a wild carcará (Caracara plancus). Case: The carcará was referred to the Veterinary Medical Teaching Hospital of the UNIUBE, at the end of May 2018, by Uberaba’s Environmental Police, with a history of having been run over. On the physical examination, the animal showed aggressive behavior, low body weight, increased heart and respiratory rates, mild dehydration and complete fracture of the rhinotheca, with avulsion of the mid-distal portion and presence of necrosis in the remaining proximal remnant, the last one seen after debridement and complete cleansing of the lesion. In the following days, complementary exams were performed aiming a complete evaluation of the animal, these revealed the following: oral cavity swab, positive for Candida sp.; radiography of thoracic and pelvic limbs, without any changes; research of hemoparasites, with a negative result; and complete blood count showing marked leukocytosis. The animal was kept in the hospital’s wild animal ward, with a daily handling of 400 g of chicken neck and heart, processed on a blender and was also supplemented with a variety of minerals. After the wild animal was managed for eleven months, evolving to the ideal weight set for the species, the process for making the prosthesis started. At first, the prosthesis was made manually with epoxy resin and polyamide, being molded on the animal's rhinotheca, before that, the carcará was sedated with intranasal midazolam, and then modeled in the ideal shape for the beak. Then, the definitive prosthesis was made with acrylic resin, using the previous mold as a base. The surgical procedure was performed in April 2019, with an anesthetic protocol composed of midazolam, dexmedetomidine, ketamine and morphine for sedation, and maintenance in sevoflurane. Prosthesis and rhinotheca were both fixated by bilateral perforation with a 1.0 mm drill, and later on 2 titanium screws were inserted for dental use, these measuring 1.5 mm. After being correctly threated, the screws received a thin layer of acrylic resin on top, for better fixation. Immediately after the operation, the animal was able to use the prosthesis to feed itself. After the surgical procedure, the bird was destined for a sanctuary, and months later the prosthesis eventually fell. Since then, the bird has remained without it.Discussion: Because the beak did not grow due to trauma and consequent necrosis, and the animal did not adapt well with the remnant still present, the manufacture of the prosthesis was the solution so that it could return to its natural habits and behaviors. For greater adherence and fixation, we opted for the use of 2 titanium screws for dental use with the deposition of a thin layer of acrylic resin on top of both. Prostheses can be successful in fixing, but there are no studies indicating how long they will remain viable. Therefore, even with the success of the procedure, allowing the bird to return to its natural habits and behaviors, until after the fall of the prosthesis, it is an animal that needs to be kept in captivity suitable for daily observation. Keywords: raptors, wild animals, beak, rhinotheca, prosthesis, synthetic, rehabilitation. Descritores: rapinantes, animais selvagens, bico, rinoteca, prótese, sintética, reabilitação.

A Novel Technique Using Polytetrafluoroethylene Tape to Solve Screw Loosening Complication in Implant-Supported Single Crowns

This study aimed to analyze a novel technique to make screws with greater untightening resistance and to solve screw loosening in implant-supported single crowns. Thirty grade IV titanium straight abutments were screwed onto 30 external hex implants using grade IV titanium screws (30 Ncm). They were exposed to cyclic loading (300,000 cycles, 200 N). Samples were divided into 4 groups (15 samples per group): new screws (SCREW group) (control), reused screws (rSCREW group), new screws wrapped with polytetrafluoroethylene (PTFE) tape (PTFE group), and reused screws wrapped with PTFE tape (rPTFE group). Reverse torque values (RTVs) were recorded with a digitally calibrated implant motor. Mean RTVs observed were 14.46 N (±1.10 N) for the control group, 14.42 N (±1.22 N) for the rSCREW group, 19.97 N (±1.16 N) for the PTFE group, and 19.13 N (±2.38 N) for the rPTFE group. Statistically significant differences were found between RTVs of both groups employing screws without PTFE tape (SCREW and rSCREW groups) compared with those using screws wrapped with PTFE tape (PTFE and rPTFE) (p < 0.001). These results suggest that wrapping the implant–abutment screw with PTFE tape may effectively lower the risk of loosening and even constitute a solution when this complication occurs in implant single crowns.